JPH0556253B2 - - Google Patents

Description

[Detailed description of the invention] Industrial applications The present invention relates to a pipe lining method.

Conventional technology and its problems The conventional method for lining a sekiway is to insert a hard or semi-hard thermoplastic pipe with a smaller diameter into the pipe, then heat the pipe and simultaneously apply pressure from inside. A method of lining pipes has been proposed, in which the pipe is inflated and closely coated on the inner surface of the pipe.

However, in the conventional method, the heating of the pipe inserted into the pipe is simply carried out from the inside of the pipe, so the heating becomes uneven in the thickness direction of the pipe, and this tendency becomes especially noticeable as the thickness increases. This non-uniform heating causes problems such as insufficient expansion, which makes it impossible to tightly coat the inner surface of the pipe, and excessive expansion, which causes cracks.

The present invention has been made with the aim of eliminating such conventional problems.

Means for Solving the Problems The present invention involves inserting a hard or semi-rigid thermoplastic tube with a small diameter into a conduit, and then heating and pressurizing this tube from the inside to expand it. In the pipe lining method, which tightly coats the inner surface, after inserting a plastic pipe into the pipe, a heating fluid is supplied between the pipe and the plastic pipe, and this heated fluid heats the pipe from the outside. The present invention relates to a pipe lining method characterized in that the pipe is expanded and the inner surface of the pipe is closely coated while simultaneously applying heat and pressure from the inside of the pipe in a conventional manner.

Embodiments The present invention will be described below based on illustrated embodiments.

When carrying out the construction method of the present invention, as shown in FIG. are connected to both ends of the conduit a, and are fitted and supported in the center of the lid portions 2a, 2a' of the terminal tubes 2, 2'. Pipe line a of the above plastic pipe 1
Insertion into the interior may be carried out with the cross-sectional shape being circular, but it may also be flattened to have a smaller cross-section and then inserted as shown in FIG.

Next, the primary steam from the primary boiler 3 is passed through the conduit 4 and the supply port _2a1 provided in the lid 2a of the one end tube 2 to the space between the conduit a and the plastic tube 1 inserted into the conduit. is supplied within 〓5, and during this time 〓5
The primary steam supplied inside the plastic pipe 1 is
while heating the other end tube 2' from the outside.
It is discharged to the outside through the discharge port 2a ₁ ' provided at a' and the discharge pipe 6 connected thereto.

During this period, the supply of primary steam into the inside of the plastic tube 1 and the heating of the plastic tube 1 from the outside by the primary steam are continued.
Secondary steam from a secondary boiler 9 is supplied into the plastic tube 1 through a supply port 7a' of a stopper 7' provided at the other end and a conduit 8 connected thereto. The secondary steam supplied into the plastic tube 1 heats the tube 1 from the inside and is discharged to the outside through the outlet 7a of the stopper 7 provided at one end and the outlet pipe 10 connected thereto. . The plastic tube 1 is heated uniformly in the direction of the tube thickness by heating from the inside and outside by primary and secondary steam, and if the tube thickness is relatively large, for example, the tube thickness is about 1 to 15 mm. Even if the tube is heated evenly in the thickness direction, it can be heated evenly in the thickness direction, and a softened state can be obtained evenly in the thickness direction. The plastic tube 1 that has been softened by heating will sag downward as shown by the dashed line in FIG. 1, but this will not interfere with the subsequent pressurized expansion operation.

After the plastic tube 1 is heated and softened, the pressure of the secondary steam inside the plastic tube 1 is increased by the pressure of the primary steam outside, and this pressure difference causes the plastic tube 1 to move as shown in FIGS. 2 and 5. As shown in FIG. 1, the tube is expanded in the radial direction while being restored to its original cross-sectional shape, and is tightly coated on the inner surface of the conduit a to form an expanded tube 1'.

After the plastic 1 is tightly coated on the inner surface of the pipe a, the supply of primary and secondary steam is stopped, and the expansion pipe 1' is cooled and solidified while the inside of the pipe is maintained at a predetermined pressure. Thereafter, by removing the terminal ends 2, 2' and cutting and removing the remaining end of the expansion tube 1', the inner surface of the conduit can be lined with the expansion tube 1' as shown in FIG.

Figures 6 and 7 show an example of heating and expanding the plastic tube 1 from the inside using secondary steam and a diameter-expanding pig 11. In this case, the diameter-expanding pig 11 is installed inside the plastic tube 1. In order to install
A gate valve 12 is installed between the other terminal pipe 2' and the pipe a, and a plastic pipe 1 is installed outside the gate valve 12.
After expanding the diameter of the plastic pipe 1 and installing the diameter-expanding pig 11 in the enlarged-diameter portion 1a, the diameter-expanding pig 11 and secondary steam are used together to expand the diameter of the plastic pipe 1 and to coat the inner surface of the pipe tightly. It is done.

In the present invention, a discharge port 14 with a steam trap 13 can be provided at the bottom end of the terminal pipe 2 in order to discharge the drain in the pipe a.

Effects In the construction method of the present invention, when pressurizing and expanding a plastic tube inserted into a conduit, the tube is heated from the inside and outside, so that heating softening in the direction of the tube thickness is uniform in all parts, and the pressure expansion of the tube is prevented. It can be carried out smoothly and without difficulty, and is extremely useful especially when using thick-walled plastic pipes.

[Brief explanation of the drawing]

Figures 1 to 3 are explanatory diagrams showing the implementation status of the construction method of the present invention in the order of steps, Figure 4 is a sectional view taken along the line ~ in Figure 1, Figure 5 is a sectional view taken along ~ in Figure 2, and Figure 6 ~
FIG. 7 is an explanatory diagram showing another implementation status of the construction method of the present invention in the order of steps. In the figure, 1 is a plastic pipe, 2 and 2' are terminal pipes, 3 is a primary boiler, 4 is a conduit, 5 is a pipe, 6 is a discharge pipe, 7 and 7' are plugs, 8 is a conduit, and 9
is the secondary boiler.

Claims (1)

[Claims] 1. A pipe lining method in which a hard or semi-rigid thermoplastic plastic pipe with a small diameter is inserted into the pipe, and then the pipe is heated and pressurized from the inside to expand and tightly coat the inner surface of the pipe. After inserting the plastic pipe into the pipe, a heating fluid is supplied between the pipe and the plastic pipe, and the heated fluid heats the pipe from the outside, and the pipe heats from the inside using a conventional method. A method for lining pipes, characterized in that the pipe is expanded and the inner surface of the pipe is closely coated while pressurizing at the same time.